Image destruct feature used with image receiving layers in secure documents

ABSTRACT

An image destruct material comprises a release layer positioned between an image receiving layer and a base layer. The adhesion between the release layer and the base layer is greater than adhesion between the release layer and the image receiving layer. The release layer material can be used in secure documents that have an image receiving layer, such as used for dye diffusion, mass transfer, ink jet, and xerographic printing. For example, particular implementations are designed for identification documents with a D2T2 image receiving layer. In these implementations, for example, the release layer is in the form of a patterned coating under the image receiving layer. After information is printed on the image receiving layer, an overlaminate is applied over it. Removal of the overlaminate destroys the printed image on the receiving layer because the relative adhesive properties of the image receiving layer, overlaminate and release layer cause the image to release with the overlaminate at the locations of the coating whereas the remainder of the image remains with the base layer.

TECHNICAL FIELD

The invention relates to secure documents and specifically features ofsecure documents that make them tamper evident to deter or preventdocument alteration and counterfeiting.

BACKGROUND AND SUMMARY

Identification documents (hereafter “ID documents”) play a critical rolein today's society. One example of an ID document is an identificationcard (“ID card”). ID documents are used on a daily basis—to proveidentity, to verify age, to access a secure area, to evidence drivingprivileges, to cash a check, and so on. Airplane passengers are requiredto show an ID document during check in, security screening and prior toboarding their flight. In addition, because we live in an ever-evolvingcashless society, ID documents are used to make payments, access anautomated teller machine (ATM), debit an account, or make a payment,etc.

For the purposes of this disclosure, ID documents are broadly definedherein, and include, e.g., credit cards, bank cards, phone cards,passports, driver's licenses, network access cards, employee badges,debit cards, security cards, smart cards (e.g., cards that include onemore semiconductor chips, such as memory devices, microprocessors, andmicrocontrollers), contact cards, contactless cards, proximity cards(e.g., radio frequency (RFID) cards), visas, immigration documentation,national ID cards, citizenship cards, social security cards, securitybadges, certificates, identification cards or documents, voterregistration cards, police ID cards, border crossing cards, legalinstruments, security clearance badges and cards, gun permits, giftcertificates or cards, membership cards or badges, etc.

Many types of identification documents carry certain items ofinformation which relate to the identity of the bearer. Examples of suchinformation include name, address, birth date, signature andphotographic image; the cards or documents may in addition carry othervariable data (i.e., data specific to a particular card or document, forexample an employee number) and invariant data (i.e., data common to alarge number of cards, for example the name of an employer). All of thecards described above will be generically referred to as “ID documents”.

FIGS. 1 and 2 illustrate a front view and cross-sectional view (takenalong the A-A line), respectively, of an identification (ID) document10. In FIG. 1, the ID document 10 includes a photographic image 12, abar code 14 (which may contain information specific to the person whoseimage appears in photographic image 12 and/or information that is thesame from ID document to ID document), variable personal information 16,such as an address, signature, and/or birthdate, and biometricinformation 18 associated with the person whose image appears inphotographic image 12 (e.g., a fingerprint, a facial image or template,or iris or retinal template), a magnetic stripe (which, for example, canbe on a side of the ID document that is opposite the side with thephotographic image), and various security features, such as a securitypattern (for example, a printed pattern comprising a tightly printedpattern of finely divided printed and unprinted areas in close proximityto each other, such as a fine-line printed security pattern as is usedin the printing of banknote paper, stock certificates, and the like).

Referring to FIG. 2, the ID document 10 comprises a pre-printed core 20(also referred to as a substrate). In many applications, the core can bea light-colored, opaque material (e.g., TESLIN (available from PPGIndustries), polyvinyl chloride (PVC) material, polyester,polycarbonate, etc.). The core 20 is laminated with a transparentmaterial, such as clear polycarbonate, PVC or polyester material 22,which, by way of example, can be about 1-10 mil thick. The composite ofthe core 20 and clear laminate material 22 form a so-called “card blank”25 that can be up to about 27 to 33 mils thick in accordance with ANSIstandards. Information 26 a-c is printed on the card blank 25 using amethod such as Laser Xerography or Dye Diffusion Thermal Transfer(“D2T2”) printing (e.g., as described in commonly assigned U.S. Pat. No.6,066,594, which is incorporated by reference). The information 26 a-ccan, for example, comprise variable information (e.g., bearerinformation) and an indicium or indicia, such as the invariant ornonvarying information common to a large number of identificationdocuments, for example the name and logo of the organization issuing thedocuments. The information 26 a-c may be formed by any known processcapable of forming the indicium on the specific core material used.

To facilitate printing of data on the card structure, an image receivinglayer is applied to the card structure prior to printing for someprinting technologies. One type of printing technology that uses animage receiving layer is D2T2 printing. U.S. Pat. Nos. 6,066,594 and5,334,573 describe image receiving layers for D2T2 printing. A sheet orlayer which is comprised of a polymer system of which at least onepolymer is capable of receiving image-forming materials from a donorsheet upon the application of heat. The polymer system of the receivingsheet or layer is incompatible or immiscible with the polymer of thedonor sheet at the receiving sheet/donor sheet interface to minimizeadhesion between the donor sheet and the receiving sheet or layer duringprinting. The polymer system of the receiving sheet or layer can besubstantially free from release agents, such as silicone-based oils,poly(organosiloxanes), fluorinated polymers, fluorine- orphosphate-containing surfactants, fatty acid surfactants and waxes.Binder materials for the dyes are immiscible with the polymer system ofthe image-receiving layer. The most common image-receiving layerpolymers are polyester, polycaprolactone and poly(vinyl chloride).Processes for forming such image-receiving layers are also described indetail in these patents; in most cases, the polymer(s) used to form theimage-receiving layer are dissolved in an organic solvent, such asmethyl ethyl ketone, dichloromethane or chloroform, and the resultantsolution coated on to the polymer layer using conventional coatingapparatus, and the solvent evaporated to form the image-receiving layer.However, if desired the image-receiving layer can be applied to thepolymer layer by extrusion casting, or by slot, gravure or other knowncoating methods.

Other forms of image receiving layers include image receiving layers forXerographic printing and inkjet printing. These image receiving layersare applied to substrates such as paper or plastic and comprisematerials that enhance reception of ink or dye to the substrate. Imagereceiving layers for Xerographic printing are sometimes referred to as“laser lock” or “toner lock.”

To protect the information that is printed, an additional layer oftransparent overlaminate 24 can be coupled to the card blank and printedinformation. Illustrative examples of usable materials for overlaminatesinclude biaxially oriented polyester or other optically clear durableplastic film.

“Laminate” and “overlaminate” include, but are not limited to film andsheet products. Laminates used in documents include substantiallytransparent polymers. Examples of laminates used in documents includepolyester, polycarbonate, polystyrene, cellulose ester, polyolefin,polysulfone, and polyamide. Laminates can be made using either anamorphous or biaxially oriented polymer. The laminate can comprise aplurality of separate laminate layers, for example a boundary layerand/or a film layer.

The degree of transparency of the laminate can, for example, be dictatedby the information contained within the identification document, theparticular colors and/or security features used, etc. The thickness ofthe laminate layers can vary and is typically about 1-20 mils.Lamination of any laminate layer(s) to any other layer of material(e.g., a core layer) can be accomplished using known laminationprocesses.

In ID documents, a laminate can provide a protective covering for theprinted substrates and a level of protection against unauthorizedtampering (e.g., a laminate would have to be removed to alter theprinted information and then subsequently replaced after thealteration.). Various lamination processes are disclosed in assignee'sU.S. Pat. Nos. 5,783,024, 6,007,660, 6,066,594, and 6,159,327. Otherlamination processes are disclosed, e.g., in U.S. Pat. Nos. 6,283,188and 6,003,581. A co-extruded lamination technology appears in U.S.patent application Ser. No. 10/692,463. Each of these U.S. patents andapplications is herein incorporated by reference.

The material(s) from which a laminate is made may be transparent, butneed not be. Laminates can include synthetic resin-impregnated or coatedbase materials composed of successive layers of material, bondedtogether via heat, pressure, and/or adhesive. Laminates also includessecurity laminates, such as a transparent laminate material withproprietary security technology features and processes, which protectsdocuments of value from counterfeiting, data alteration, photosubstitution, duplication (including color photocopying), and simulationby use of materials and technologies that are commonly available.Laminates also can include thermosetting materials, such as epoxy.

Manufacture Environments

Commercial systems for issuing ID documents are of two main types,namely so-called “central” issue (CI), and so-called “on-the-spot” or“over-the-counter” (OTC) issue.

CI type ID documents are not immediately provided to the bearer, but arelater issued to the bearer from a central location. For example, in onetype of CI environment, a bearer reports to a document station wheredata is collected, the data are forwarded to a central location wherethe card is produced, and the card is forwarded to the bearer, often bymail. Another illustrative example of a CI assembling process occurs ina setting where a driver renews her license by mail or over theInternet, then receives a drivers license card through the mail.

A CI assembling process is more of a bulk process facility, where manycards are produced in a centralized facility, one after another. (Forexample, picture a setting where a driver passes a driving test, butthen receives her license in the mail from a CI facility a short timelater. The CI facility may process thousands of cards in a continuousmanner.).

Centrally issued identification documents can be produced from digitallystored information and generally comprise an opaque core material (alsoreferred to as “substrate”), such as paper or plastic, sandwichedbetween two or more layers of clear plastic laminate, such as polyester,to protect the aforementioned items of information from wear, exposureto the elements and tampering. U.S. Pat. No. 6,817,530, which is herebyincorporated by reference, describes approaches for manufacturingidentification documents in a central issue process.

In contrast to CI identification documents, OTC identification documentsare issued immediately to a bearer who is present at a document-issuingstation. An OTC assembling process provides an ID document“on-the-spot”. An example of an OTC assembling process is a Departmentof Motor Vehicles (“DMV”) setting where a driver's license is issued toa person, on the spot, after a successful exam. In some instances, thevery nature of the OTC assembling process results in small, sometimescompact, printing and card assemblers for printing the ID document.

OTC identification documents of the types mentioned above can take anumber of forms, depending on cost and desired features. Some OTC IDdocuments comprise highly plasticized poly(vinyl chloride) or have acomposite structure with polyester laminated to 0.5-4.0 mil (13-104.mu.m) poly(vinyl chloride) film on the outside of typical PVC orComposite cards, which provides a suitable image receiving layer forheat transferable dyes which form a photographic image, together withany variant or invariant data required for the identification of thebearer. These data are subsequently protected to varying degrees byclear, thin (0.125-0.250 mil, 3-6 .mu.m) overlay patches applied at theprinthead, holographic hot stamp foils (0.125-0.250 mil 3-6 .mu.m), or aclear polyester laminate (0.5-10 mil, 13-254 .mu.m) supporting commonsecurity features. These last two types of protective foil or laminatesometimes are applied at a laminating station separate from theprinthead. The choice of laminate dictates the degree of durability andsecurity imparted to the system in protecting the image and other data.One form of overlay is referred to as a “transferred panel” or“O-panel.” This type of panel refers to a panel in the print ribbon thatis transferred to the document with the use of the printhead.

From the standpoint of security, an identification document should bedifficult to tamper with and/or provide clear evidence of tampering. Inparticular, the various layers of the document, including the laminate,should be difficult to separate or intrude into without severelydamaging the document and marring the information contained in it.

One way to protect the integrity of a secure document is to useoverlaminate technology. Currently, PVC and composite cards used insecure ID documents rely on the overlaminate or a “transferred panel”(e.g., O-panel) to both physically protect the variable data printed onthe card and to provide security for this data. In these card systems,the overlaminate is expected to fracture along a plane or tear when acounterfeiter attempts to remove it, resulting in an unusable card.Though this removal typically renders the overlaminate unusable, theremainder of the card is still usable in many cases. In some cases, bothare re-usable. This allows the counterfeiter to alter or reuse thepersonalized card and, if needed, replace the overlaminate or panel witha substitute.

In view of this drawback of existing technology, there is a need formore effective document materials and methods to protect documentintegrity and prevent successful document alteration and counterfeiting.

The invention provides an image destruct feature for use in securedocuments. It also provides secure document structures including thisfeature and methods for making the feature and documents including it.

One aspect of the invention is an image destruct material comprising arelease layer positioned between an image receiving layer and a baselayer. The adhesion between the release layer and the base layer isgreater than adhesion between the release layer and the image receivinglayer. The release layer material can be used in secure documents thathave an image receiving layer, such as used for dye diffusion, masstransfer, ink jet, and xerographic printing. For example, particularimplementations are designed for identification documents with a D2T2image receiving layer. In these implementations, for example, therelease layer is in the form of a patterned coating under the imagereceiving layer. After information is printed on the image receivinglayer, an overlaminate is applied over it. Removal of the overlaminatedestroys the printed image on the receiving layer because the relativeadhesive properties of the image receiving layer, overlaminate andrelease layer cause the image to release with the overlaminate at thelocations of the coating whereas the remainder of the image remains withthe base layer.

Other aspects of the invention include alternative image destructmaterials, release layer formulations, and methods for making imagedestruct features for secure documents.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages, features, and aspects of embodiments of the inventionwill be more fully understood in conjunction with the following detaileddescription and accompanying drawings, wherein:

FIG. 1 is an illustrative example of an identification document;

FIG. 2 is an illustrative cross section of the identification documentof FIG. 1, taken along the A-A line;

FIG. 3 is a diagram illustrating a cross section of a document structureincluding a release layer between an image receiving layer and baselayer that forms a tamper evident, image-destruct feature;

FIG. 4 is a diagram illustrating a cross section of a document structurewith an alternative image destruct feature; and

FIG. 5 is a flow diagram illustrating a method of making a securedocument with a release layer between image receiving and base layers.

Of course, the drawings are not necessarily drawn to scale, withemphasis rather being placed upon illustrating the principles of theinvention. In the drawings, like reference numbers indicate likeelements or steps. Further, throughout this application, certainindicia, information, identification documents, data, etc., may be shownas having a particular cross sectional shape (e.g., rectangular) butthat is provided by way of example and illustration only and is notlimiting, nor is the shape intended to represent the actual resultantcross sectional shape that occurs during manufacturing of identificationdocuments.

DETAILED DESCRIPTION

For purposes of illustration, the following description will proceedwith reference to ID document structures (e.g., TESLIN-core, PVC-core orPolycarbonate-core, multi-layered ID documents). It should beappreciated, however, that the invention is not so limited. Indeed, asthose skilled in the art will appreciate, the inventive techniques canbe applied to many other structures formed in many different ways.

FIG. 3 is a diagram illustrating a cross section of an identificationdocument including a release layer (e.g., 106 a-c) between an imagereceiving layer 102 and base layer 104 that forms a tamper evident,image-destruct feature. In this embodiment, the release layer is in theform of a patterned coating deposited underneath an image receivinglayer 102. The materials of these three layers are chosen such thatadhesion of the patterned coating to the base is much greater thanadhesion of the coating to the image receiving layer. In particular, theadhesion of the patterned coating to the base is high or fused. Adhesionbetween the patterned coating and the image receiving layer positionedimmediately above this patterned coating is either weak or non-existent.In this embodiment, the patterned coating covers less than the entiresurface of the base such that portions of the image receiving layerdirectly contact the base. The adhesion of the balance of the imagereceiving layer to the base is equal to or greater than the adhesion ofthe patterned layer to the base. The release layer can be chemicallyfused or blended with the base as well making an indestructible bond tothe base.

Layer 100 in FIG. 3 represents an overlaminate. For ID documentapplications, the overlaminate is chosen to protect the printing on theimage receiving layer. An example of an overlaminate is a 1 MILpolyester film that is laminated over the image receiving layer afterprinting and joined to the underlying materials with an adhesive. Theoverlaminate is typically applied over the entire surface of the IDdocuments being manufactured. Typically, the image receiving layercovers the entire surface of the document as well. However, it is alsopossible to place the image receiving layer or layer in selectedlocations on the document surface. The adhesion between the overlaminateand the image receiving layer is stronger than the adhesion between theimage receiving layer and the release layer. When the overlaminate isremoved (e.g., as a result of tampering or intrusion by acounterfeiter), the printed image fractures, and the parts of the imageover the release layer remain adhered to the overlaminate (e.g., animage in the form of the pattern of the coating goes with theoverlaminate). Other parts of the printed image and image receiver layerremain adhered to the base. The adhesive of the overlaminate is suchthat removal of the overlaminate destroys it. In addition, the weakadhesion of the image receiving layer to the release pattern ensures thedestruction of the D2T2 image when the overlaminate is removed.

Preferably, the design of a release layer for use with an imagereceiving layer has the following objectives: 1) achieve a high level ofadhesion to the base; 2) achieve a low or non-existent level of adhesionto the image receiving layer; 3) mitigate interference of the patternedcoating with the lay down of the image receiving layer or layers; 4)mitigate interference of the patterned layer with the printingoperation; and 5) achieve the first two objectives across the relevanttemperature span of interest (typically, room temperature to 230 F).

Particular embodiments of the release layer are designed for use withD2T2 image receiving layers. Regarding item 3, the release layer ischosen to have a non-resolubilization character so that the D2T2 imagereceiving layer's solvents do not dissolve or excessively soften therelease layer. Solvents sometimes cause a swelling and/or softening of apolymer material if they are able to invade that material. Theresolubilization character mitigates the impact of any solvent from theimage receiving layer on the release layer. As noted, the basic releaselayer approach also applies for documents having image receiving layersused for inkjet and Xerographic printing.

For secure document applications, the base layer forms part of adocument structure typically comprising layers of film fused together.These film layers are input to the manufacturing process as sheets orrolls of film called “webs.” The various layers are processed, joinedand die cut to form individual documents, such as blank card stock orpersonalized ID documents. The base web can be a variety of materialsused in identification documents, but is typically a polymer film, suchas polycarbonate or PVC film, to name a few examples. The specificmaterial used as the base layer may vary, and formulations of therelease layer and image receiving layer are designed to accommodate theselected base material.

FIGS. 3-4 emphasize only pertinent aspects of the overlaminate, imagereceiving layer, release layer and base layer. A typical ID documenttypically has more layers, and the base layer itself may be fused fromtwo or more layers. In one card structure, a light colored, opaque corelayer of TESLIN® or polycarbonate is fused with one or more layers oftransparent polycarbonate (e.g., front and back layers). In another, asingle or double core of white PVC is fused with clear outer laminatelayers. In yet another, outer layers of biaxally oriented polyesterreinforce a core layer or layers of PVC. Additional layers as well asalternative card structures can be used with the overlaminate, imagereceiving layer, and base layers described in this document.

Two specific example embodiments are described further below, followedby a description of a method for making secure, tamper evident IDdocuments with a release layer.

In a first example embodiment, the release layer is coated out ofalcohol and composed of a water soluble polymer and solvent solublepolymer blend. In particular, it comprises KLUCEL®hydroxypropylcellulose/polyamide blend. This blend ensures that there isno resolubilization of the release layer when the D2T2 image receivinglayer is coated immediately on top. This results in a relatively flatand low profile patterned coating and is easily integrated into theproduction process involving the lay down of D2T2 via gravure. FIG. 3depicts a document structure where the image receiving layer 102 andoverlaminate are relatively flat. The size of the elements of thepattern coating (106 a-c) are exaggerated in FIG. 3 so that they aremore noticeable. In an actual implementation, the patterned coating hasa relatively flat and low profile on the surface of the base layer 104,resulting in relatively flat surfaces of both the image receiving layer102 and overlaminate 100.

FIG. 4 is a diagram illustrating a cross section of a document structurewith an alternative release layer. This diagram illustrates thepertinent structure of a second example embodiment, which uses materialsand processing that creates a raised, and potentially visible andtactile feature on the surface of the document. This feature can beviewed and felt to verify the presence of the release layer. In thisexample, the release layer (110 a-c) comprises a UV cured formulationapplied directly to a base layer 112 (e.g., polycarbonate web) andsubsequently cured. This formulation yields a coating proud of thesurface. It may require subsequent coatings of D2T2 image receivinglayer 114 via slot or reverse roll to apply sufficient fluid so as tonot interfere with the first lay down of the release pattern. Thisprocess produces a secure card where the feature is quite prominent andwhen printed leaves a non-dye transferred fringe around the entirepattern. One can easily see this as a “white” border defining thepattern of the release layer. This border remains “white” or“un-printed” (i.e., the color of the base layer) due to the fact thatthe D2T2 print head does not transfer dye due to the interaction of theprinthead, ribbon and surface characteristics of the pattern at therising and falling edges of the release pattern's borders.

Additionally, the overlaminate 116 is “embossed” when laminated over theprinted card's surface taking on the exact proud feature set of thepatterned coating. This gives yet another feature in that the secureoverlaminate is now embossed in the exact same pattern as the “imagedestruct” feature. The UV cured coating 100 a-c does not change itsnature over a wide temperature range (e.g., room temperature to 230 F)rendering the image destruct feature's performance constant over a widetemperature range (for intrusion). This same characteristic allows forthe embossing feature to occur since it remains rigid while thelamination occurs.

As an additional security feature, security inks, such as UV, IR,optically variable inks, Pearlescent, etc. (“specialty”) inks, areoptionally used to print fixed or variable indicia 118 a-c on or in thebase layer 112. See, for example, U.S. Pat. No. 6,827,277, which ishereby incorporated by reference. In the example shown, the securityinks are positioned below portions of the document where the releasepattern 10 a-c is located. These specialty inks may be printed in apattern arranged relative to the release pattern to create desiredoptical effects, such as the appearance of spatially and visuallyinterlocking specialty ink and release patterns that change in color orposition as the document is rotated about a viewing angle or illuminatedwith an illumination source in different wavelength bands. The releasepattern and security ink indicia can be located in mutually exclusivelocations on the document surface.

FIG. 5 is a flow diagram illustrating a method of making a securedocument with a release layer between image receiving and base layers.First, the base layer is prepared (step 200). Preparation of the baselayer may include printing information (such a fixed indiciacorresponding to the issuer) on a light-colored, opaque polymersubstrate or core layer. Optionally, a transparent film is laminated onthe core. The baser layer comprises the core with or without printing orthe transparent film.

Next, a coating machine applies the release layer to the base layer(step 202). One such coating machine is a gravure printer. Other coatingmethods may be used as well. In the case where the coating is a curablematerial, the base layer with coating applied is cured (e.g., via UV orEB curing). As described above, the coating may be applied to coverselected portions of each document. Examples include applying thecoating in the form of a graphical symbol (e.g., seal of the issuer),text, or form of halftone image.

Next, the image receiving layer is applied over the release layer (step204). It may be applied by extrusion casting, or by slot, gravure orother known coating methods. Examples of image receiving layers areprovided below. At this point, individual cards may be die cut fromsheets of the document structure and distributed to card issuingfacilities as card blanks.

Next, an image is printed on the image receiving layer (step 206). Forexample, variable, personalized data of the document bearer is printedon the image receiving layer. For OTC ID cards with D2T2 image receivinglayers, OTC D2T2 printers are used to print the bearer's photo, personalinformation, and possibly other data at an issuing facility.

Finally, an overlaminate is laminated onto the card (step 208).

EXAMPLES

In one class of embodiments of our release coating formulation, we blendtwo type polymers in the release coating. One has stronger releaseproperty and the other has better adhesion to both a PVC image receivingcoating and polycarbonate substrate. The one with strong releaseproperty includes polyvinyl alcohol, polysaccharide, Cellulose, andmodified cellulose such as cellulose acetate butyrate, polyvinylbutyral, or hydroxypropyl cellulose (e.g. like KLUCEL®). This type ofmaterial has less compatibility with polycarbonate and PVC materials. Itmainly functions to break the images on the image receiving layer uponintrusion. The other type of polymer with better adhesion to a PVC imagereceiving layer coating and polycarbonate layer includes polyamide,polyurethane, polystyrene, or polyacrylate. This type of polymer willact as a bridge to hold a PVC image receiving layer coating on thepolycarbonate document material. We prefer to use a blend of polyamideand KLUCEL®. The ratio of polyamide to KLUCEL® is ranged from 80/20 to20/80. And the coating thickness will range from 0.01 to 1 micron. Aparticular formulation is: KLUCEL ® 2.5% Polyamide 2.5% Iso propanolalcohol  45% n-propanol alcohol  45%

The coating thickness is about 0.2 micron.

In another class of embodiments, we use a UV curable release coating. Inthis case, a UV cured release coating provides strong adhesion to thepolycarbonate substrate, but weak bond to the PVC image receiving layer.The coating composition includes a polymer binder, a UV curable oligomerand monomer, and UV curable initiators. The binder includes polystyrene,polyacrylate, or polyester. The binder provides certain adhesion to thePVC coating. Oligomers and monomers include urethane acrylate, epoxyacrylate, and ester acrylate. These materials produce a networkstructure upon curing.

Example 1 for screen printing: wt. (g) wt. % CN966H90 272.11 30% SR9041256.08 28% SR351 82.81  9% SR399 245.89 27% Sr1129 48  5% Total 904.89100% 

Example 2 for gravure printing: wt. (g) wt. % Butyl acrylate   6% SR90415.6% SR351 1.9% SR399 3.4% Sr1129   1% MEK  80% Total 100% 

The release pattern works in a variety of line widths and graphic imagedesigns. We have made samples with release patterns in the form of alogo, and different line widths ranging from about 0.01″ to 0.03″.Currently, we have selected 0.03″ line widths for our prototype product.In some embodiments, we form the release pattern as a set of linestructures (e.g., a set of wavy lines in parallel applied along thelonger dimension of a rectangular ID card).

As noted previously, the release layer technology can be used in avariety of ID card types, including polycarbonate cards, dualpolycarbonate and TESLIN® cards, PVC cards, and composite cards (e.g.,cards including alternating biaxally oriented polyester and PVC layers).For example in one ID card production process, the process starts withan opaque polycarbonate or TESLIN® core, applies a clear polycarbonatelayer to the core, applies the release pattern to the clearpolycarbonate layer, applies an image receiving layer over the releasepattern, and cuts the result into individual blank card stock. At thetime of issuance, a printer prints personal information on the imagereceiving layer and applies an overlaminate. In some cards, like PVC orcomposite cards, the core comprises PVC or a combination of polyesterand PVC. For such cards, a typical card production process applies a 2-5mil layer of clear PVC layer over the core, and that PVC layer canfunction as an image receiving layer. However, to integrate the releasepattern, the production process is modified to include application of arelease layer over the clear PVC layer, which serves as the base layer,followed by application of an image receiving layer (e.g., another PVCbased formulation) over the release layer. As in the other case, theresulting structure is then cut into blank card stock. After printing onthe outer image receiving layer at the time of issuance, an overlaminateis applied to complete the card. As this example demonstrates, it ispossible to integrate the release pattern into structures thatinherently have thermal transfer image receiving layer functionality(such as some forms of PVC cards), as well as card structures that donot.

Below are some examples of D2T2 image receiving layer formulationsusable with the above document materials and methods.

Example 1

Components and Formulation: Solid % Solvent  89.80% MEK(100%) PVC(Oxychem-155)    10% BYK-306  0.20% 100.00%

Example 2

Components and Formulation: Solid % Solvent 86.30%  MEK PVC(Oxychem-155) 13.5% BYK-306 0.20%

The following image receiving layer formulations include a copolymer,plasticizer, and antioxidant. This combination increases printing dyedensity and film stability.

Example 3

Total Wet 15 Dry Solid % Solid % 20.00% Component Stk. % % % Wt. kgVYNS-3 100% 73% 14.60% 2.19 Dioctyl phthalate 100% 23% 4.60% 0.69 IRANOX245 100%  1% 0.20% 0.03 TINUVIN 5050 100%  3% 0.60% 0.09 MEK 100% 12Total 100%  15

Example 4

Mixture Total wt 50 solid % 10.00% Component Stk. % Ratio Wet Wt % Wt.kg Solvents Acetone 100% 80 72.00% 36 Diacetone Alcohol 100% 20 18.00% 9Solids VYNS-3 100% 73% 7.30% 3.65 Dioctyl phthalate 100% 23% 2.30% 1.15IRGANOX 245 100%  1% 0.10% 0.05 TINUVIN 5050 100%  3% 0.30% 0.15 Total100%  50Procedure:1) Charge acetone into the mixer.2) Add DOP into acetone solvent with agitation.3) Add Irganox 245 into the mixer with agitation.4) Add Tinuvin 5050 into the mixture with agitation.5) After the mixture solution becomes clear, add VYNS-3 slowly into themixture with proper agitation6) After the mixture is fully dissolved, add diacetone alcohol into thefinal solution and mix for another hour.

Example 5

Mixture Total wt 50 solid % 10.00% Component Stk. % Ratio Wet Wt % Wt.kg Solvents Acetone 100% 80 72.00% 36 Diacetone Alcohol 100% 20 18.00% 9Solids VYNS-3 100% 73% 7.30% 3.65 Dioctyl phthalate 100% 23% 2.30% 1.15IRGANOX 245 100%  1% 0.10% 0.05 TINUVIN 5050 100%  3% 0.30% 0.15 Total100%  50Procedure:

1) Charge acetone into the mixer.

2) Add DOP into acetone solvent with agitation.

3) Add Irganox 245 into the mixer with agitation.

4) Add Tinuvin 5050 into the mixture with agitation.

5) After the mixture solution becomes clear, add VYNS-3 slowly into themixture with proper agitation.

6) After the mixture is fully dissolved, add diacetone alcohol into thefinal solution and mix for another hour.

CONCLUDING REMARKS

Having described and illustrated the principles of the technology withreference to specific implementations, it will be recognized that thetechnology can be implemented in many other, different, forms, and inmany different environments.

The technology disclosed herein can be used in combination with othertechnologies. Also, instead of ID documents, the inventive techniquescan be employed with product tags, product packaging, labels, businesscards, bags, charts, smart cards, maps, labels, etc. The term IDdocument is broadly defined herein to include these tags, maps, labels,packaging, cards, etc.

It should be understood that, in the Figures of this application, insome instances, a plurality of method steps may be shown as illustrativeof a particular method, and a single method step may be shown asillustrative of a plurality of a particular method steps. It should beunderstood that showing a plurality of a particular element or step isnot intended to imply that a system or method implemented in accordancewith the invention must comprise more than one of that element or step,nor is it intended by illustrating a single element or step that theinvention is limited to embodiments having only a single one of thatrespective elements or steps. In addition, the total number of elementsor steps shown for a particular system element or method is not intendedto be limiting; those skilled in the art will recognize that the numberof a particular system element or method steps can, in some instances,be selected to accommodate the particular user needs.

To provide a comprehensive disclosure without unduly lengthening thespecification, applicants hereby incorporate by reference each of theU.S. patent documents referenced above.

The technology and solutions disclosed herein have made use of elementsand techniques known from the cited documents. Other elements andtechniques from the cited documents can similarly be combined to yieldfurther implementations within the scope of the present invention.

Thus, the exemplary embodiments are only selected samples of thesolutions available by combining the teachings referenced above. Theother solutions necessarily are not exhaustively described herein, butare fairly within the understanding of an artisan given the foregoingdisclosure and familiarity with the cited art. The particularcombinations of elements and features in the above-detailed embodimentsare exemplary only; the interchanging and substitution of theseteachings with other teachings in this and the incorporated-by-referencepatent documents are also expressly contemplated.

In describing the embodiments of the invention illustrated in thefigures, specific terminology is used for the sake of clarity. However,the invention is not limited to the specific terms so selected, and eachspecific term at least includes all technical and functional equivalentsthat operate in a similar manner to accomplish a similar purpose.

1. An image destruct material comprising: an image receiving layeroperable to receive variable image printing; and a release layerpositioned between the image receiving layer and a base layer, adhesionbetween the release layer and the base being greater than adhesionbetween the release layer and the image receiving layer.
 2. The materialof claim 1 comprising an overlaminate applied over the image receivinglayer, wherein the release layer comprises a coating applied in apattern and an image printed on the image receiving layer destructsalong the pattern in response to removal of the overlaminate.
 3. Thematerial of claim 1 wherein the image receiving layer comprises acoating including a solvent, and the coating includes anon-resolubilization characteristic to reduce swelling or softening ofthe release layer by the image receiving layer.
 4. The material of claim3 wherein the release layer comprises hydroxypropylcellulose andpolyamide.
 5. The material of claim 1 wherein the release layercomprises a UV curable formulation.
 6. The material of claim 5 whereinthe UV curable formulation forms a raised pattern.
 7. The material ofclaim 6 wherein the raised pattern of the release layer forms a raisedpattern in an overlaminate layer when overlaminated.
 8. An imagedestruct material comprising: a release coating positioned between andye diffusion image receiving layer and a base layer, adhesion betweenthe release coating and the base being greater than adhesion between therelease layer and the image receiving layer.
 9. The material of claim 8comprising an overlaminate applied over the image receiving layer,wherein the release layer is applied in a pattern and an image printedon the image receiving layer destructs along the pattern in response toremoval of the overlaminate.
 10. The material of claim 8 wherein thecoating includes a solvent, and the coating includes anon-resolubilization characteristic to reduce swelling or softening ofthe release coating by the image receiving layer.
 11. The material ofclaim 10 wherein the release coating comprises hydroxypropylcelluloseand polyamide.
 12. The material of claim 8 wherein the release coatingcomprises a UV curable formulation.
 13. The material of claim 12 whereinthe UV curable formulation forms a raised pattern, and the raisedpattern of the release layer forms a raised pattern in an overlaminatelayer when overlaminated.
 14. A method for making a security feature fora document comprising: applying a release layer to an area of a baselayer; applying an image receiving layer to the release layer; andapplying an overlaminate over the image receiving layer, whereinadhesion between the release layer and the base layer is greater thanadhesion between the release layer and the image receiving layer suchthat removal of the overlaminate causes an image printed on the imagereceiving layer to separate with the overlaminate in the area of therelease layer while the image printed on the image receiving layerremains with the base outside the area of the release layer.
 15. Themethod of claim 14 wherein the image receiving layer comprises a D2T2image receiving layer.
 16. The method of claim 14 wherein the releaselayer comprises a water soluble polymer and a solvent soluble polymer,and the release layer has a resolubilization characteristic to mitigateswelling or softening in response to applying the image receiving layeron the release layer.
 17. The method of claim 14 comprising: curing therelease layer on the base layer.
 18. A release coating for use increating a tamper evident feature for secure documents: a water solublepolymer and a solvent soluble polymer, the coating having aresolubilization characteristic to mitigate swelling or softening inresponse to applying an image receiving layer on the release layer, andthe coating having substantially no adhesion to an image receivinglayer.
 19. The release coating of claim 18 wherein the water solublepolymer comprises hydroxypropylcellulose and the solvent soluble polymercomprises polyamide.
 20. The release coating of claim 18 wherein theimage receiving layer comprises a D2T2 image receiving layer. 21-25.(canceled)